Expansible mandrel.



No. 727,000. PATBNTED MAY 5, 1903.'- re. H. sHATTUcK an H. R.H FARNSWORTH.

EXPANSIBLE MANDRBL.

APPLIOATION FILED KAY 27, 1902.

UNITED STATES Patented May 5, 1903.

Y PATENT QEEICE.

GEORGE H. SHTTUCK AND I-IILAND R. FARNSWORTH, OF TURNERS FALLS,

i MASSACHUSETTS,

EXPANSIBLE MANDREL.

SPECIFICATION forming part of Letters Patent No., 727,000, dated May 5, 1903.

Application filed May2-7,1902. Serial No. 109.154. (No model.)

To all whom, t may concern:

Be it known that We, GEORGE H. SHATTUCK and HILAND R. FARNSWORTH, citizens of the United States, residing at Turners Falls,in the county of Franklin and State of Massachusetts, have invented certain new and useful Improvements in Expansible Mandrels; and We do hereby declare that the following is a full, clear, and exact description of the invention, which will enable others skilled in the art to which it appertains to make and use the same.

Our invention relates to a class of expansible mandrels in' which the outer cylinder or shell, composed -of longitudinal segmental plates, is expanded orV contracted by means of oppositely-disposed .contiguous rows of sloping steps or inclined planes formed, respectively, upon the inner faces of the said plates and the exterior of the central shaft. As the segments are forced in one direction their inclined planes or steps ascend those of the shaft, and the segments are thereby crowded outward, thereby expanding the effective diameter of the mandrel, while uponv a reverse movement of the segments their steps descend those of the shaft, and the mandrel is contracted.

In most if not all of the expansible mandrels heretofore in use the segmental plates of the outer cylinder are operated from the interior of the central shaft, which is hollow, and usually by a screw-threaded rod. In our mandrel we operate and adjust the segments of the expansible cylinder by means of nuts screwed upon opposite ends of the solid central shaft and abutting against the ends of the segments, respectively, and in order to automatically effect the contraction of the segments, aswell as to prevent them from dropping oif or being accidentally detached fromv the shaft, we employ with each segment one or more (preferably two) guideplns, secured to its inner face and capable of sliding in corresponding pockets in the periphery of the shaft, these guide-pins being of course parallel to the faces of the sloping steps before alluded to.

By operating the segments from the outside, as explained, we are enabled' to use a comparatively small solid shaft and to construct the entire mandrel in a very compact, solid, and stiff manner, While by the employment of the sloping steps the segments find a practically continuous bearing upon the solid shaft.

It will be apparent that the greater the number of the sloping steps (with a given depth) the more rapid will be the expansion and contraction of the outer cylinder and the less the extent of longitudinal movement of the segments requisite to effect a given amount of such expansion and contraction, or the same result would be attained by increasing the depth of the steps. Y

The drawings accompanying this specification represent, in Figure l, a part elevation part longitudinal section, enlarged as compared with the scale of the accompanying figures, of an expansible mandrel embodying our invention. Fig. 2 denotes an elevation ofthe mandrel with the nuts and one segkment removed, while FigJS represents an isometric View of one of the segments of the outer eXpansible cylinder.

In the drawings, l represents a solid cylindrical shaft, upon each end of which is cut a peripheral screw-thread 2, while engaging each of these screw-threads is a nut 3. At certain points (four in the present instance) upon the periphery of the shaft l we form or secure a longitudinally-disposed fange or rack of sloping steps or inclined planes 4 4:, dto., the angle of these steps with respect to the axis of the shaft being determined by the amount or rapidity of expansion desired.

The segmental plates, which in aggregate constitute the outer periphery of the mana drel, (and which in the present instance are four in number,) are shown at 5 5, &c the length of these segments being practically equal to the distance between the nuts3 3. The inner face of each segment is provided with a longitudinally-disposed range' of steps or inclined planes 6, which correspond in size and slope with those of the shaft upon which they bear. The endwise adjustment of the segments upon the shaft are, as will readily be seen, effected by the nuts 3 3, which abut against their opposite ends, one nut being IOO advanced as the other is retracted, and vice versa, according to Whether the mandrel is to be expanded or contracted.

To automatically contract the segments, as well as to prevent their accidental detachment from the shaft, we provide guide-pins 7, parallel with the inclined faces of the steps and in each instance attached to or for-med- With one of the elements or parts, having an inclined face in contact with another inclined face, each of the said pins tting into a pocket of corresponding shape, depth, and inclination in the opposite part or element. Thus in Fig. l We have shown the pins attached to the shaft by cross-pins and fitting. into pockets formed in the proximate segment; but of course this arrangement may be reversed and the means lof attachment varied. The guide-pins must be at least equal in number to the segments. It is preferable to employ two such pins for each segment, as shown in Fig. 1.

In lieu of duplicate nuts screwing upon each vend of the shaft, as explained, a single nut, swiveledto one end of the shaftuandengaging screw-threads cut upon the ends `of the segments, may be employed; but We pre-k fer the duplicate nuts, as providing greater security and strength. p'

We claim- 1. In an expanding mandrel, a solid centhe same inclination as the said inclined faces and the said plates being provided with correspondingly-inclined pockets to receive the said pins substantially as set forth.

2. In an expanding mandrel the combination of a solid central shaft and external plates, with means for moving the said plates longitudinally on the said shaft, the shaft and plates being provided with correspondingly-inclined faces and the said shaft being provided with pins of similar inclination that enter corresponding pockets of the plates to prevent the'separation of the latter as well as to guide them substantially asset forth.4

In testimony whereof We affix our signatures in presence of two witnesses.

GEO. H. SHATTUCK. HILAND R. FARNSWORTH.

E. A. BARDWELL, WILLIAM P. ARGY, J r. 

